[ruby-core:45998] [ruby-trunk - Feature #5138] Add nonblocking IO that does not use exceptions for EOF and EWOULDBLOCK

Issue #5138 has been updated by rosenfeld (Rodrigo Rosenfeld Rosas).


Aaron, with due respect, I'm not sure if the examples in your slide are good enough for promoting it. The logic looks like the same in both current and proposed version. Maybe some use cases where the current approach would require too much code would demonstrate better why the new approach is helpful. Unless you're gonna to present the slide yourself or make sure the presenter will discuss the pros and contras of each approach.
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Feature #5138: Add nonblocking IO that does not use exceptions for EOF and EWOULDBLOCK
https://bugs.ruby-lang.org/issues/5138#change-27602

Author: wycats (Yehuda Katz)
Status: Assigned
Priority: Normal
Assignee: matz (Yukihiro Matsumoto)
Category: core
Target version: 1.9.4


The current Ruby I/O classes have non-blocking methods (read_nonblock and write_nonblock). These methods will never block, and if they would block, they raise an exception instead (IO::WaitReadable or IO::WaitWritable). In addition, if the IO is at EOF, they raise an EOFError.

These exceptions are raised repeatedly in virtually every use of the non-blocking methods. This patch adds a pair of methods (try_read_nonblock and try_write_nonblock) that have the same semantics as the existing methods, but they return Symbols instead of raising exceptions for these routine cases:

* :read_would_block
* :write_would_block
* :eof

The patch contains updates for IO, StringIO, and OpenSSL. The updates are fully documented and tested.


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